The eosinophil granulocyte in psoriasis

Unveiling multifaceted roles of myeloid innate immune cells in the pathogenesis of psoriasis

Psoriasis is a chronic inflammatory skin disease occurring worldwide. Initially viewed as a keratinocyte disorder, psoriasis is now recognized to involve a complex interplay between genetic predisposition, environmental triggers, and a dysregulated immune system, with a significant role of CD4+ T cells producing IL-17. Recent genetic studies have identified susceptibility loci that underscore the importance of innate immune responses, particularly the roles of myeloid cells, such as dendritic cells, macrophages, and neutrophils. These cells initiate and sustain inflammation through cytokine production triggered by external stimuli. They influence keratinocyte behavior and interact with adaptive immune cells. Recent techniques have further revealed the heterogeneity of myeloid cells in psoriatic lesions, highlighting the contributions of less-studied subsets, such as eosinophils and mast cells. This review examines the multifaceted roles of myeloid innate immune cells in psoriasis, emphasizing their functional diversity in promoting psoriatic inflammation. It also describes current treatment targeting myeloid innate immune cells and explores potential new therapeutic strategies based on the functional characteristics of these subsets. Future research should focus on the detailed characterization of myeloid subsets and their interactions to develop targeted treatments that address the complex immune landscape of psoriasis.

Dermatomyositis with Eosinophils

Dermatomyositis is an idiopathic inflammatory myopathy that often presents with symmetric proximal skeletal muscle weakness and characteristic skin findings. Typical skin biopsy findings include vacuolar changes of the basal layer, increased dermal mucin, and a predominantly lymphocytic infiltrate. We report a case of dermatomyositis presenting as intensely pruritic papules and plaques, with initial histopathology being atypical of dermatomyositis due to the presence of eosinophils. The initial biopsy demonstrated a superficial dermatitis with eosinophils, initially thought to represent a drug eruption. A second biopsy of the same cutaneous manifestation was performed at a later time given high clinical suspicion for dermatomyositis and demonstrated a more classic vacuolar interface dermatitis with increased mucin and an absence of eosinophils. Notably, increased pruritus was specifically associated with the lesion that demonstrated tissue eosinophilia. The case illustrates the importance of considering tissue eosinophilia in the histologic presentation of dermatomyositis.

Eosinophils Accelerate Pathogenesis of Psoriasis by Supporting an Inflammatory Milieu that Promotes Neutrophil Infiltration

Eosinophils are proinflammatory granulocytes that are involved in the pathogenesis of various inflammatory reactions. However, their roles in psoriasis remain largely unknown. In this study, by examining the inflammatory features of the eosinophilic cell line EoL-1 and an imiquimod-induced murine model of psoriasis, we show that eosinophils provide inflammatory signals that accelerate the pathogenesis of psoriasis. EoL-1 cells constitutively expressed TLR7, which mediates acute and rapidly developing psoriatic inflammation. The activation of TLR7 on EoL-1 cells using R837 resulted in the secretion of inflammatory mediators that support the migration, activation, and survival of neutrophils. The underlying pathologic role of eosinophils in psoriatic inflammation was further substantiated by markedly decreased psoriasiform inflammation in imiquimod-treated ΔdblGATA mice, which have a systemic eosinophil deficiency. While imiquimod-treated wild-type mice showed a significant increase in the eosinophils in their skin, neutrophils remarkably outnumbered the eosinophils in the skin, lymph nodes, and spleen in wild-type mice after imiquimod application. In addition, lesional skin samples from psoriasis patients also showed up-regulated eosinophil cytotoxic granules, accompanied by marked neutrophil infiltration. Based on these collective data, we propose that eosinophils accelerate psoriatic inflammation by supporting inflammatory microenvironments to favor the activation and infiltration of neutrophils.

Peripheral blood eosinophilia in association with generalized pustular and erythrodermic psoriasis

BACKGROUND

In recent studies, it has been documented that the eosinophil cells play active role in many kinds of inflammatory disorders. Measurements of the mediators released by eosinophils and cell counts in serum and skin have provided some evidence indicating the role of eosinophils in psoriasis.

OBJECTIVE

To evaluate the blood eosinophil cell count in patients with erythrodermic psoriasis and generalized pustular psoriasis.

METHODS

In this study, 48 patients with histopathologically proven psoriasis (33 with erythrodermic, 15 with generalized pustular); 43 patients with maculopapular, erythematous, or bullous drug eruption with widespread involvement; and 51 patients with basal cell carcinoma were included. These three groups were compared with each other in terms of their absolute eosinophil cell counts and percentage of eosinophils.

RESULTS

Forty-one point seven per cent of patients with psoriasis had peripheral blood eosinophilia compared with 58.1% of the patients with drug eruption and 11.8% of patients with basal cell carcinoma. The percentage of patients with eosinophilia both in patients suffering from psoriasis and drug eruption were significantly increased compared with the patients with basal cell carcinoma (P < 0.001). The absolute median eosinophil cell counts both in patients with psoriasis and drug eruption were also significantly differed from patients with basal cell carcinoma (259.2, 439.1 and 183.1, respectively; P < 0.001)

CONCLUSIONS

Peripheral blood eosinophilia seems to be associated with severe forms of psoriasis. This finding may suggest that the eosinophils have significant roles in the pathogenesis of these types of psoriasis.

Regulatory mechanisms of galectin-9 and eotaxin-3 synthesis in epidermal keratinocytes: possible involvement of galectin-9 in dermal eosinophilia of Th1-polarized skin inflammation

BACKGROUND

Skin eosinophilia is a common feature of allergic skin diseases, but it is unclear how epidermal and dermal eosinophil infiltration is controlled. To investigate regulation of localization of eosinophils in skin, we examined the regulatory mechanisms of expression of eosinophil-specific chemoattractants in dermal fibroblasts and epidermal keratinocytes.

METHODS

We analyzed production of eotaxin, eotaxin-2, eotaxin-3 and galectin-9 by dermal fibroblasts and epidermal keratinocytes in response to several stimuli in vitro.

RESULTS

Dermal fibroblasts produced eotaxin and eotaxin-3 in response to stimulation by interleukin (IL)-4 and/or tumor necrosis factor-alpha. Similarly, IL-4 stimulated epidermal keratinocytes to secrete eotaxin-3. However, we did not detect eotaxin mRNA expression or protein secretion by keratinocytes stimulated in vitro. Interferon (IFN)-gamma induced galectin-9 expression on dermal fibroblasts. Conversely, expression of galectin-9 on epidermal keratinocytes was dose-dependently inhibited by IFN-gamma. The immunohistochemical assays revealed that dermal fibroblasts (but not epidermal keratinocytes) in the lesional skin of psoriasis vulgaris (a Th1-polarized disease) express significant levels of galectin-9.

CONCLUSION

Eotaxin-3 contributes to dermal and epidermal eosinophil infiltration in Th2-polarized skin inflammation in which IL-4 is produced. In contrast, IFN-gamma-dominated inflammation appears to mediate eosinophil extravasation into the dermis and eosinophil adhesion to dermal fibroblasts via galectin-9 in association with decreased chemoattractant activity of epidermal galectin-9. The present results reveal a novel mechanism of dermal eosinophilia in IFN-gamma-mediated skin inflammation, and reflect concerted chemoattractant production involving dermal and/or epidermal eosinophilia during changes in the local cytokine profile.

Vasoactive intestinal peptide regulates its receptor expression and functions of human keratinocytes via type I vasoactive intestinal peptide receptors

Vasoactive intestinal peptide has been suggested to play some roles in inflammatory dermatoses such as atopic dermatitis and psoriasis. The aim of this study is to clarify the precise mechanisms of how vasoactive intestinal peptide is implicated in the pathogenesis of these disorders. We investigated the expression of vasoactive intestinal peptide and its receptors in normal human fibroblasts and keratinocytes, as well as in a human epidermal keratinocyte cell line DJM-1, using reverse transcription polymerase chain reaction and northern blotting. Type I VIP receptor mRNA was expressed in normal human keratinocytes and DJM-1 cells, and the latter also expressed type II receptor in lesser amounts. Neither type I nor type II VIP receptor mRNA was detected in fibroblasts, and vasoactive intestinal peptide transcript was not found in any cells examined. Type I VIP receptor mRNA was upregulated by Th1 cytokines (interferon-gamma), Th2 cytokines (interleukin-4), and tumor necrosis factor alpha, as well as vasoactive intestinal peptide itself, suggesting the presence of an autoregulatory loop. Vasoactive intestinal peptide increased cAMP production and cell proliferation of DJM-1 cells, and also induced the production of inflammatory cytokines such as interleukin-6, interleukin-8, and RANTES. The production of cAMP and cytokines was abrogated by a type I VIP receptor selective antagonist, indicating that type I receptor mediates these effects. Overall, these results suggest that upregulation of vasoactive intestinal peptide receptors by cytokines from inflammatory cells in the dermis enhances the proliferation and cytokine production of keratinocytes in response to vasoactive intestinal peptide from nerve endings. This cytokine network around keratinocytes may be involved in the pathogenesis of inflammatory dermatoses.

Activated and non-activated eosinophils in patients with chronic rhinosinusitis

Nasal polyps develop out of an oedematous swelling of the mucous membrane, which is probably a localized mediator-dependent reaction of the mucous membrane in the lamina propria. Among other things, eosinophil cationic protein (ECP) is released from activated eosinophils. In previous studies, ECP was considered as measuring the degree of allergic dermatological illnesses and therapy was given accordingly. A group of 54 patients with massive polyposis requiring functional endoscopic sinus surgery was examined. After surgery they were treated with local and systemic cortisone. Polypous tissue samples were collected and counted for the number and ratio of activated and non-activated eosinophils, and the serum titre of ECP was measured simultaneously using a fluoroimmunoassay (test kit, Kabi Pharmacia, Sweden). The aim of the study was to evaluate the activity of the disease and to gain hints for a specific therapy. The presence of these eosinophils was demonstrated by immunohistochemical methods, using EG1 antibodies against non-activated and EG2 antibodies against activated (i.e. secreted form of ECP) eosinophils. Depending on the duration of treatment with systemic and local corticosteroids, there was a considerable decrease in activated eosinophils and the level of serum ECP. Consequently, cortisone can be applied in the treatment of eosinophilic nasal polyps. As the number of activated eosinophils in the tissue is an indicator for the activity of the chronic inflammation it can be deduced from our study that local and/or systemic cortisone application successfully stops the growth of eosinophilic nasal polyps. The number and ratio of activated and non-activated eosinophils seem to be reliable indicators for the activity of chronic polyposis.

Palmoplantar pustulosis: a clinical and immunohistological study

Pustulosis palmoplantaris (PPP) is a common chronic skin disease, which is very resistant to treatment. It is not known why the lesions are located in the palms and soles. There are few studies of the disease and in particular studies of the histology. Fifty-nine patients with PPP answered a questionnaire concerning their medical history and 39 of them were clinically examined. Biopsy specimens were taken from involved skin in 22 of the 39 patients and studied immunohistologically for tryptase+ mast cells, EG2+ eosinophils, lipocalin+ neutrophils and CD3+ T lymphocytes. The sweat gland and sweat duct were visualized with AE1/AE3 antibody (cytokeratins 1-8, 10, 14/15, 16, 19). In addition to neutrophils in the pustule and lymphocytes in the upper dermis, there were also large numbers of mast cells and eosinophils in the subpustular area. Numerous eosinophils were present in the pustule. The epidermal part of the eccrine duct was not detectable in any of the specimens from patients with PPP but was present in all of the nine control persons (including two smokers). The results indicate that the acrosyringium is involved in the inflammation and also that mast cells and eosinophils participate in a hitherto unknown way. Of the 39 patients clinically examined, two had previously diagnosed thyroid disease and two had gluten hypersensitivity. Seventeen had one or several abnormal serum concentrations of thyroid-stimulating hormone, thyroxin, antibodies against thyroglobulin or thyroperoxidase and 10 had immunoglobulin (Ig) A antibodies to gliadin. The mean +/- SD for serum IgA and for eosinophil cationic protein was increased. From the questionnaire the most notable finding was that 56 of the 59 patients had been or still were smokers, all of whom had started smoking before the first signs of PPP. We hypothesize that the acrosyringium might be the target for the inflammation and that PPP is linked to autoimmune thyroid disease and smoking.

RANTES expression in psoriatic skin, and regulation of RANTES and IL-8 production in cultured epidermal keratinocytes by active vitamin D3 (tacalcitol)

The chemokine RANTES is a chemoattractant for eosinophils, T lymphocytes of memory phenotype and monocytes, suggesting that it plays an important part in chronic inflammatory and allergic diseases. In various types of cells, RANTES production is markedly induced by tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma in combination. Psoriasis vulgaris is a chronic cutaneous inflammatory disease. Cytokines and chemokines produced by T cells and epidermal keratinocytes, such as interleukin (IL) 8, are involved in the pathogenesis of psoriasis. T-cell clones obtained from psoriatic skin have been shown to produce the Th1 cytokine IFN-gamma. In addition, abnormal expression of proinflammatory cytokines including TNF-alpha has been observed in psoriatic lesions. These reports led us to hypothesis that psoriatic skin could provide epidermal keratinocytes with TNF-alpha and IFN-gamma, so that keratinocytes could produce RANTES. In this study, we addressed the question as to whether RANTES was involved in psoriasis vulgaris. Immunohistochemistry of skin biopsies showed RANTES was present in the intercellular spaces between epidermal keratinocytes, in the fully developed lesions from the middle to the edge of psoriatic plaques, but not in the perilesional uninvolved and healthy control skin. Further, we confirmed the production of RANTES, together with IL-8, by cultured normal human epidermal keratinocytes, using an enzyme-linked immunosorbent assay. Stimulation with TNF-alpha and IFN-gamma in combination synergistically increased the RANTES production in this system. These results clearly demonstrate the expression of RANTES in psoriatic lesions and suggest the involvement of this chemokine in the outcome of cutaneous inflammatory diseases. Tacalcitol (1 alpha,24(R)-dihydroxyvitamin D3), an active vitamin D3 analogue, inhibited RANTES and IL-8 production in cultured normal epidermal keratinocytes. This result indicates that active vitamin D3 is effective in the regulation of chemokine production by epidermal keratinocytes, which may partly account for its action as an antipsoriatic drug.

Monitoring of serologic immune parameters in inflammatory skin diseases

This paper deals with the correlation of clinical scoring and serologic markers of inflammation in atopic dermatitis and psoriasis. Serum eosinophil cationic protein (ECP), soluble interleukin-2 receptor (sIL-2R), total serum IgE, IgG and IgM anti-IgE antibodies, and IgE immune complexes were evaluated in monitoring inflammatory skin diseases such as atopic dermatitis and psoriasis. Well-established clinical activity scores were used as standards in recording skin improvement under treatment in a clinical setting. Serum ECP was found to be increased in both atopic dermatitis and psoriasis patients compared to normal controls; sIL-2R and IgE immune complexes were increased only in atopics with increased serum IgE. Anti-IgE antibodies did not show any deviation in both groups of patients. There was a significant elevation of sIL-2R and IgE immune complexes and a nonsignificant elevation of ECP in high-IgE atopics in comparison to those with normal serum IgE. In both groups of patients, there was a significant reduction of ECP and sIL-2R accompanying the improving skin condition. Serum IgE and the other immune parameters failed to respond. In contrast to other studies, serum ECP failed to correspond significantly with disease activity in our study. Our results showed measurable changes of ECP and sIL-2R for atopic dermatitis and/or psoriasis under treatment, but comparison to clinical scores remains difficult due to the different basis of the two systems. The only significant correlation was established for relative changes in sIL-2R and psoriasis area and intensity (PASI), a correlation which might be a useful approach in psoriasis.

Eosinophil cationic protein (ECP) level and its correlation with eosinophil number or IgE level of peripheral blood in patients with various skin diseases

Eosinophil cationic protein (ECP) is a cationic protein derived from eosinophil granulocytes, and has been studied mainly in atopic diseases and considered as a useful marker of disease activity in atopic dermatitis. We measured the serum ECP levels in patients with various skin diseases (n = 875) and in normal healthy controls (n = 79), and evaluated the correlation between ECP level and blood eosinophil number, or ECP and IgE levels. Serum ECP levels were significantly higher in patients with drug eruption (15.8 +/- 1.7 micrograms/l), psoriasis (15.1 +/- 6.0 micrograms/l), acute urticaria (13.9 +/- 1.4 micrograms/l) than in healthy controls (4.5 +/- 0.3 micrograms/l) (P < 0.05) and also significantly elevated in patients with elevated eosinophil numbers (15.2 +/- 1.0 micrograms/l) compared to those in patients with normal eosinophil numbers (8.8 +/- 0.3 micrograms/l) (P < 0.001). Serum ECP level and eosinophil number in peripheral blood were also correlated in patients with psoriasis (gamma = 0.82, P < 0.01), drug eruption (gamma = 0.31, P < 0.01) and acute urticaria (gamma = 0.20, P < 0.05). However, no correlation between ECP and IgE levels in all of the patients was found. Among the patients with chronic urticaria, ECP levels showed an increasing trend in patients with angioedema, cold urticaria and dermographic urticaria as compared with those in healthy controls. Our results suggest that, even though the role of ECP released from activated eosinophils is still unknown, its measurement might be of help to understand the pathogenesis of some skin disorders.

Patients with psoriasis have elevated levels of serum eosinophil cationic protein and increased numbers of EG2 positive eosinophils in the duodenal stroma

The occurrence of EG2-positive (EG2+) eosinophils and IgE in biopsy specimens of duodenal mucosa and skin from 39 psoriasis patients was studied, with emphasis on the relation to serum eosinophil cationic protein (ECP), serum IgE and the presence or absence of serum IgA and IgG antigliadin antibodies. Psoriasis patients had significantly elevated serum levels of ECP even after exclusion of five of 37 sera which were Phadiatop positive. The elevated serum ECP was not associated with the presence of IgA or IgG antibodies to gliadin. After exclusion of Phadiatop positive sera the serum IgE values did not differ from those of a group of healthy blood donors. Patients with psoriasis had a pronounced increase of EG2+ cells in their duodenal stroma. Patients without antibodies to gliadin tended to have even more EG2+ cells than those with such antibodies and those with increased duodenal intraepithelial lymphocytes. IgE+ cells were present in most duodenal specimens, and in some specimens there were > 100 IgE+ cells/section. The number of EG2+ cells was increased in lesional skin and, in some patients, also in non-involved skin, but there was a more pronounced increase in EG2 reactivity in the duodenal than in the skin specimens. IgE reactivity was increased both in non-involved and involved skin and was significantly related to the number of IgE-positive cells in the duodenal stroma. The results of this study indicate that the gastrointestinal tract and the eosinophil granulocyte might be involved in psoriasis in a hitherto unknown way.

T lymphocytes derived from skin lesions of patients with psoriasis vulgaris express a novel cytokine pattern that is distinct from that of T helper type 1 and T helper type 2 cells

In various immunological disorders the pathomechanisms of tissue damage are causally associated with specific patterns of locally produced cytokines. To study the molecular and cellular mechanisms involved in the manifestation of psoriasis vulgaris we have assessed the cytokine mRNA profile expressed in lesional psoriatic skin and in T cell clones (TCC) that were established from skin lesions of patients with psoriasis. As demonstrated by use of the polymerase chain reaction (PCR), psoriasis lesions consistently exhibit transcription of a complex pattern of cytokines. It includes mediators selectively produced by T lymphocytes [interferon (IFN)-gamma, tumor necrosis factor (TNF)-beta, interleukin (IL)-2, IL-3 and IL-5] as well as cytokines secreted by various cell types [transforming growth factor (TGF)-alpha/-beta, TNF-alpha, IL-6/-8 and granulocyte-macrophage-colony stimulating factor], while IL-4 is missing. With the exception of TGF-alpha, this cytokine profile was also observed in lesional psoriatic T cell clones yielding supernatants mitogenic for keratinocytes in vitro (MTCC), but not in T cell clones yielding supernatants that inhibited keratinocyte proliferation (STCC). The congruent cytokine expression of psoriatic skin lesions and MTCC emphasizes that inflammation in psoriasis is driven by a sofar unrecognized regulatory T cell subset that may serve to control epidermal regeneration and convey immunosurveillance over epithelial surfaces. It is characterized by the combined expression of IFN-gamma, TGF-beta, IL-2 and IL-5 in the absence of IL-4 and by its selective capacity to enhance keratinocyte proliferation. This newly defined combination of regulatory properties of a distinct T cell population cannot be reconciled with an immune response of the T helper cells (TH)0, TH1 or TH2 type.

Monoclonal antibody EG2 does not provide reliable immunohistochemical discrimination between resting and activated eosinophils

The monoclonal antibody (mAb) EG2 has been considered to identify activated eosinophils and several immunohistochemical reports of EG2+ eosinophils in various allergic and other inflammatory disorders have suggested an important pathogenic role for such cells. This study showed that cellular EG2 reactivity, both in peripheral blood and mucosal tissue preparations, depends mainly on the method of sample preparation. Nearly 100% of blood eosinophils from normal individuals were strongly EG2+ when prepared by formalin fixation, whereas only a fraction reacted in the unfixed (64%) or acetone-fixed (60%) state. A significantly increased (p < 0.03) number of EG2+ cells were likewise detected in cryo-sections of inflamed nasal mucosa after formalin fixation compared with acetone fixation. Moreover, virtually all eosinophils were EG2+ in cryo-sections of normal jejunal mucosa fixed in periodate-lysine-(0.5%) paraformaldehyde prior to freezing. Conversely, EG2 reacted only weakly, or failed to react, with many eosinophils in cryo-material not subjected to such pre-fixation, in contrast to adjacent non-eosinophilic cells which were brightly stained. Two-colour immunofluorescence consistently revealed overlapping labelling with EG2 and mAb EG1 or a polyclonal antibody to eosinophil cationic protein in sections of formalin-fixed, paraffin-embedded normal gastrointestinal mucosa. Our findings thus showed that EG2 does not provide reliable immunohistochemical discrimination between resting and activated eosinophils. When optimal pre-fixation of tissue specimens was omitted, EG2 reactivity appeared to be caused, at least in part, by leached antigen adsorbed to adjacent non-eosinophilic cells.

Human eosinophils stimulate DNA synthesis and matrix production in dermal fibroblasts

Fibrosis is frequently found in diseases exhibiting tissue eosinophilia, such as some parasitic worm infections, eosinophilia-myalgia syndrome, and eosinophilic fasciitis. Previously, eosinophil extracts have been shown to induce proliferation in neonatal foreskin fibroblasts in vitro. To determine if living eosinophils can induce synthesis of DNA and components of the extracellular matrix in dermal fibroblasts, we cultured purified human eosinophils for 2 or 7 days in the presence of the eosinophil-active cytokines granulocyte/macrophage colony stimulating factor, interleukin-3, or interleukin-5, and added eosinophil-conditioned medium to cultures of dermal fibroblasts. Using flow cytometry, we found that eosinophil-conditioned medium increased by two-fold the percentage of fibroblasts in S-phase. This stimulation of fibroblast DNA synthesis was corroborated using a standard tritiated thymidine assay and the two methods were shown to correlate well with each other. Eosinophil-conditioned medium stimulation of DNA synthesis was dose dependent and conditioned medium from eosinophils treated with any one of the three cytokines induced increased DNA synthesis. Treatment of fibroblasts with cytokines alone did not induce enhanced DNA synthesis. Eosinophil-conditioned medium also affected fibroblast matrix production. Eosinophil-conditioned medium induced a two-fold increase in soluble and cell-associated fibroblast glycosaminoglycan production and a 76% increase in collagen production. These observations support the concept that eosinophils may be active contributors to the pathophysiology of eosinophil-associated fibrotic disease.

Eosinophil cationic protein in sera of patients with atopic dermatitis

Patients with atopic dermatitis frequently show elevated blood eosinophil counts, and eosinophil-derived major basic protein has been demonstrated in the eczematous skin from patients with atopic dermatitis. To evaluate further the role of eosinophils in the pathogenesis of atopic dermatitis, the concentration of eosinophil cationic protein was measured in serum samples of 42 patients with moderate to severe disease. The results were compared with those obtained in 32 patients with psoriasis with (n = 9) or without (n = 23) a history of inhalant allergy, 12 patients with a history of pseudoallergic reactions to acetylsalicylic acid, 14 patients with a history of inhalant allergy, and 31 nonatopic healthy control subjects. Eosinophil cationic protein levels were significantly increased in the serum of patients with atopic dermatitis (p less than or equal to 0.005) and patients with a history of pseudoallergic reactions to acetylsalicylic acid (p less than or equal to 0.01). There was no significant difference between eosinophil cationic protein levels in patients with psoriasis or a history of inhalant allergy and in control subjects. Moreover, eosinophil cationic protein levels did not differ significantly in psoriasis patients with or without inhalant allergy. These studies support the concept of an active participation of eosinophils in atopic dermatitis and point to a possible role for eosinophils in pseudoallergy.